Seven Inmates Killed in Prison Riot in Northern Mexico

Mexican security officials say seven inmates have died in a prison riot on the outskirts of the northern Mexican city of Monterrey.

Authorities say military and federal officials were called in to quell the riot early Thursday after prison staff failed to control the fighting.

Local reports say the rioting may have started after inmates learned of the arrest of Carlos Olivia Castillo, a key figure in the Zetas drug cartel. He was arrested Wednesday after an hours-long gunfight with security officials in the northern city of Saltillo.

Olivia Castillo allegedly ordered the torching of a Monterrey casino in August, which killed 52 people. That incident was one of the country's worst attacks against civilians in decades.

Olivia Castillo was the number-three man within the Zetas organization. His arrest was part of a larger offensive launched in August in three northern states against the country's drug cartel. The army has since arrested more than 700 suspected criminals and seized several-hundred weapons.